“…Geological and geophysical evidence suggests that lower crustal deformations are often perturbed by shear localization to produce shear zones in a viscous regime [52,53]. Such deep-crustal (>18km) shear zones display their internal band structures with varied geometry, as observed in the CGGC [18,43] and other high-grade metamorphic terrains [1,2,32,54,55]. Our simple shear zone model envisages the evolution of complex band geometry as a consequence of the competing shear band localization mechanisms: Riedel, C and P, determined by the effective thickness (Wc), bulk shear rate and bulk viscosity of shear zones.…”
Section: Discussionmentioning
confidence: 99%
“…Ductile shear zones often show emplacement of quartz and calcite veins along the secondary shear bands. Figure 2A simplified geological map of the East Indian Precambrian craton, showing the disposition of the Chotanagpur Granite Gneiss Complex (CGGC) (modified after Roy et al [18]; Mazumder et al [39]; Saha [40]; Sengupta et al [41]; Dasgupta et al [42]; Chattopadhyay et al [43]). Detailed geological map of the two major study areas: (a) Mukutmanipur region and (b) Purulia region.…”
Ductile yielding of rocks and similar solids localize shear zones, which often show complex internal structures due to the networking of their secondary shear bands. Combining observations from naturally deformed rocks and numerical modelling, this study addresses the following crucial question: What dictates the internal shear bands to network during the evolution of an initially homogeneous ductile shear zone? Natural shear zones, observed in the Chotonagpur Granite Gneiss Complex of the Precambrian craton of Eastern India, show characteristic patterns of their internal shear band structures, classified broadly into three categories: type I (network of antithetic low-angle Riedel (R) and synthetic P-bands), type II (network of shear-parallel C and P/R bands) and type III (distributed shear domains containing isolated undeformed masses). Considering strain-softening rheology, our two-dimensional viscoplastic models reproduce these three types, allowing us to predict the condition of shear band growth with a specific network pattern as a function of the following parameters: normalized shear zone thickness, bulk shear rate and bulk viscosity. This study suggests that complex anastomosing shear-band structures can evolve under simple shear kinematics in the absence of any pure shear component.
“…Geological and geophysical evidence suggests that lower crustal deformations are often perturbed by shear localization to produce shear zones in a viscous regime [52,53]. Such deep-crustal (>18km) shear zones display their internal band structures with varied geometry, as observed in the CGGC [18,43] and other high-grade metamorphic terrains [1,2,32,54,55]. Our simple shear zone model envisages the evolution of complex band geometry as a consequence of the competing shear band localization mechanisms: Riedel, C and P, determined by the effective thickness (Wc), bulk shear rate and bulk viscosity of shear zones.…”
Section: Discussionmentioning
confidence: 99%
“…Ductile shear zones often show emplacement of quartz and calcite veins along the secondary shear bands. Figure 2A simplified geological map of the East Indian Precambrian craton, showing the disposition of the Chotanagpur Granite Gneiss Complex (CGGC) (modified after Roy et al [18]; Mazumder et al [39]; Saha [40]; Sengupta et al [41]; Dasgupta et al [42]; Chattopadhyay et al [43]). Detailed geological map of the two major study areas: (a) Mukutmanipur region and (b) Purulia region.…”
Ductile yielding of rocks and similar solids localize shear zones, which often show complex internal structures due to the networking of their secondary shear bands. Combining observations from naturally deformed rocks and numerical modelling, this study addresses the following crucial question: What dictates the internal shear bands to network during the evolution of an initially homogeneous ductile shear zone? Natural shear zones, observed in the Chotonagpur Granite Gneiss Complex of the Precambrian craton of Eastern India, show characteristic patterns of their internal shear band structures, classified broadly into three categories: type I (network of antithetic low-angle Riedel (R) and synthetic P-bands), type II (network of shear-parallel C and P/R bands) and type III (distributed shear domains containing isolated undeformed masses). Considering strain-softening rheology, our two-dimensional viscoplastic models reproduce these three types, allowing us to predict the condition of shear band growth with a specific network pattern as a function of the following parameters: normalized shear zone thickness, bulk shear rate and bulk viscosity. This study suggests that complex anastomosing shear-band structures can evolve under simple shear kinematics in the absence of any pure shear component.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
